FR2865511A1 - Manufacturing procedure for elastic joint used e.g. in vehicle axle and suspension systems uses two concentric blocks of different elastic materials - Google Patents

Abstract

The procedure for making an elastic joint comprising outer and inner solid tubular components joined by an elastic material such as rubber uses two different elastic materials in concentric blocks that are joined together directly or through a thin tubular intermediate element with a generally cylindrical contact surface. The procedure for making an elastic joint comprising outer and inner solid tubular components joined by an elastic material such as rubber uses two different elastic materials in concentric blocks that are joined together directly or through a thin tubular intermediate element with a generally cylindrical contact surface. The two elastic blocks are moulded simultaneously, using vertical and/or horizontal injection units and a press (6) with a top plate (63), an upper mould plate (60), upper and lower mould impression holders (61, 62).

Description

The present invention relates to a method of manufacturing a device

elastic articulation.

  This type of device is intended to ensure the connection between two movable elements relative to each other.

  It is used in particular in the field of transport and more particularly in the axles, suspensions, engine anti-torque devices of an automobile, a truck or any other rolling vehicle, for example a locomotive or a railway wagon. iron. More specifically, it finds a particular application in the field of the ground connection, particularly in the case of the connection between the body and a cradle, a deformable axle or a triangle of an automobile.

  In the usual manner, an elastic hinge device as described for example in document FR-A-2 715 702, comprises a tubular outer frame surrounding a central core which is also tubular and coaxial, this frame being made integral with the core by a mass of elastic material, of the natural rubber or elastomer type.

  The function of such a device is to ensure the connection and filtering of vibrations between two elements, for example between the body of a vehicle and the wheel. For this purpose, the core is traversed by an axial central opening which makes it integral with the body of a vehicle, while the outer sleeve is connected to the hub of one of the vehicle wheels. Reverse mounting is also possible.

  The road behavior of a vehicle requires a level of value of high dynamic and static stiffness of the elastic material, for each direction of the vehicle.

  To improve the vibratory behavior, it is necessary to increase the level of damping (at the frequency of the mode to be damped), in particular for the longitudinal direction of the vehicle.

  Acoustically, the desire is to lower the level of stiffness, to reduce rolling noise and preferably for the vertical direction of the vehicle.

  The difficulty is to reconcile the level of dynamic stiffness and the level of damping, which is different according to the main directions of the articulation device.

  Dynamic stiffness and damping depend on amplitude level and frequency. On the other hand, the higher the value of an elastomer with a high damping value, the more the dynamic stiffness increases according to the aforementioned parameters. Indeed, there is no material with high damping value, which stiffens little.

  Therefore, the choice of an elastomer is often the compromise between a high damping and a slight stiffening, which is inconsistent with the nature of the elastomer.

  Another solution is to choose to opt for a first satisfactory value (for example in terms of damping) by accepting that the second value is degraded.

  Yet another solution is to use two elastomers having different properties, by assembling several hinge devices mounted concentrically. But this translates into a high cost.

  The present invention aims to provide a method of manufacturing a resilient hinge device that allows not to compromise between a high damping and a little stiffening, this without significant additional cost.

  Thus, this method of manufacturing a resilient hinge device intended to allow the articulation of two elements relative to each other, of the type comprising an axial tubular outer frame adapted to be fitted into the first element, a central tubular core adapted to be connected to the second element, mounted inside said armature and having an axis parallel to the latter, and a mass of elastic material interconnecting said outer armature and said central core, which is consisting of at least a first block of a first material having a high damping value and at least a second block of a second material having a low stiffening value, these first and second blocks being contiguous and having a contact surface which extends exclusively in a substantially transverse direction, is essentially characterized by the fact that it is molded simultaneously, in particular p ar injection, the so-called first and second blocks.

  Thus, the device thus manufactured has at least one block of elastic material (for example rubber) damping in the direction in which it is sought to dampen and at least one block of elastic material which stiffens little, if it is desired to mitigate this increase in stiffness to reduce the noise.

  Throughout the present application, including in the claims, the expression "contact surface which extends exclusively in a substantially transverse direction" means that this surface extends in a generally cylindrical direction. , coaxial with the frame and core, or that it extends in a substantially radial direction. In any case, this definition excludes a contact surface located in a plane perpendicular to the longitudinal axis of the device, that is to say the case where the two blocks are superimposed in the longitudinal direction.

  Furthermore, it is also understood that the two blocks can be in direct contact as well as through a tubular element of small thickness.

  Moreover, according to a certain number of characteristics of this process: the molding is carried out by injection, and two vertical injection units are used; a vertical injection unit and a horizontal injection unit are used; two horizontal injection units are used; said blocks are coaxial; - Between the two blocks is interposed a tubular element, split or not, thin, coaxial with said reinforcement and core; said blocks are distributed according to substantially identical angular sectors; - the number of sectors is equal to two; - The number of sectors is equal to four, which are distributed alternately, the blocks of the same material being preferably diametrically opposed; said device has at least one recess in the contact zone of said blocks; said outer armature comprises, at at least one of its ends, a peripheral collar which is coated with elastic material, which constitutes an axial abutment; said elastic material is made of the same material as that of the first block or the same material as that of the second block, or a mixture of the two; said tubular reinforcement and central core are coaxial.

  Other features and advantages of the invention will appear on reading the following description with reference to the accompanying drawings in which: - Figure 1 is a sectional view along a transverse median plane 5 of a first embodiment the hinge device manufactured according to the method of the invention; FIG. 2 is a perspective view of the device of FIG. 1; - Figure 3 is a sectional view along a longitudinal median plane of the same device; FIG. 4 is a diagram intended to illustrate the behavior of the device of FIGS. 1 to 3; FIGS. 5 and 6 are sectional views, respectively along longitudinal and transverse median planes, of a second embodiment of the device; - Figure 7 is a sectional view along a transverse median sectional plane of a third embodiment of the device; - Figures 8 and 9 are diagrams for illustrating two variants of the method of manufacturing by molding the elastic material blocks which constitute the device; - Figure 10 is a perspective view of a device and the distribution channels of the elastic material.

  Before describing the method of manufacturing the hinge device, we will describe hereinafter the actual structure of this device.

  The device shown in FIG. 1 comprises an outer armature 1, a central core 2 and an elastomer mass 3.

  The outer armature 1 has an elongated tubular shape, of axis Y-Y ', the sectional section is circular. It is intended to be fitted into the bore of a first of the two elements to be articulated with respect to one another.

  Its outer and inner walls were respectively numbered 10 and 11.

  At its upper end, it has a peripheral collar 12, consisting of a right-angled flap directed outwards.

  The central core 2 consists of a tube of approximately square cross-section, mounted coaxially inside the armature 1. It is intended to be connected to the second element to isolate vibrations, for example by means of a clevis .

  Its length is slightly greater than that of the frame and it is positioned so that its ends coming out of the frame have substantially the same dimension.

  This tube has a central and axial bore 20. Its outer and inner walls 5 have been respectively numbered 21 and 22.

  The outer frame 1 is made of thermoplastic material or metal, especially steel or aluminum. The central core 2 is made of a material able to withstand the mechanical stresses that the joint undergoes during use. It is advantageously a metal, such as steel or aluminum.

  The mass of elastic material 3, rubber type elastomeric material, interconnects the two aforementioned parts and ensures the articulation and filtering of vibrations.

  In the embodiment described here, the mass of elastic material extends essentially in the middle part of the surface of the walls facing the armature 1 and the core 2, so that two spaces E, of identical volume, are arranged on either side of the elastomer mass. In other words, these annular spaces E communicate on the one hand with the elastomer mass and with the outside by the opposite ends of the armature.

  The elastomer mass here consists of two blocks 30 of a first material having a high damping value and two blocks 31 of a second material having a low stiffness value.

  These blocks are distributed in substantially identical angular sectors (90) and are organized so that the blocks 30 and 31 of the same material are diametrically opposed.

  According to a variant not shown, these blocks can be distributed in different angular sectors, for example respectively 110 and 70.

  Their mutual contact surface S therefore extends along radial planes angularly arranged in a median manner with respect to the Y-Y 'and Z-Z' axes of the device.

  These are plans in which the articulation is not brought to be solicited. This is advantageous in terms of the lifetime of the mutual contact between the blocks.

  This surface is here very limited because the blocks have in these regions recesses F. The material constituting the blocks extends against the inner face 11 of the frame 1 to cover the flange 12, thereby constituting an abutment axial. The flange may consist either exclusively of the material which constitutes the blocks 30, or of that which constitutes the blocks 31, or of a mixture thereof.

  Very schematically shown on the left side of Figure 4 a device obtained according to the method of the invention. The above-mentioned blocks have been represented here in the form of rubber rolls P1 and P2 of axis Z-Z 'and rubber rolls P3 and P4 of axis X-X'. This device can be represented symbolically as shown on the right part of the same FIG. 4, namely in the form of two parallel flat plates Al and A2, connected by two rubber bars P5 and P6 connected in parallel.

  For a stress on X-X ', the rubber rolls P3 and P4 will work mainly in compression and rubber rolls P1 and P2 located in the Z-Z' direction will work mainly in shear.

  Conversely, for Z-Z 'stressing, the rubber rolls in the X-X' direction will work mainly in shear and the rubber rolls in the Z-Z 'direction will work mainly in compression.

  The dynamic stiffness of a rubber element consists of a real and imaginary part: K * = K '+ iK "= K' (1 + iK" / k ') = K' (1 + itgcp) with tgcp = K "/ K 'and K * = modulus of the dynamic stiffness K' = real part of the dynamic stiffness K" = imaginary part of the dynamic stiffness Note: the damping of a joint being weak, we have: K *, -Z, K 'For rubber rolls in the direction XX': KX * = K ,, '+ iKX' For rubber rolls in the direction ZZ ': KZ * = KZ' + iKZ "For the whole the bi-material joint thus constituted, the dynamic stiffness will be: = Kx * + KZ * = Kx '+ + Kz + = Kx' + Kz + i (Kx "+ KZ ') = K ,, + KZ' [1 + i (Kx "+ KZ") / (Kx '+ KZ')] = Kx '+ Kz' [1 + i (Kx'.Kx "/ K, '+ Kz'.K," / K, I ( Kx '+ Kz] = Kx' + Kz [1 + i (K x 'Kx' / Kx' + KZ'.k "/ Kz) / (Kx '+ Kz)] = Kx' + Kz [1 + i ( Kx'.tg + Kz.tg) / (Kx '+ Kz)] If tg = K ,, "/ Kz and tg = KZ" / Kz Then we have: K * = K' (1 + i tgq5), with K '= K ,, + Kz K "= Kx'.tgcpx + K,'. Tgcp, Tgcp = (Kx'.tgcpx + Kz.tgcpZ) / (KX + Kz) The damping of a bi-material joint is therefore the center of gravity of the rubber rolls in the X-X 'direction and the damping in rubber rolls in the Z-Z' direction. Their respective coefficients are their actual stiffness.

Example

  By finite element calculation, the stiffness fraction is decomposed along the X-X 'and Z-Z' directions of the rubber bars located along the X-X 'and Z-Z' directions.

  The rubber roll in the X-X 'direction will have a strong damping to dampen the axle modes while the rubber bread in the Z-Z' direction will have a low damping so as not to stiffen and thus generate little rolling noise.

  Breads Z Breads X Total K tgcp Kx 23 70 93 0.20 Ky 12 11 23 0.15 Kz 165 14 179 0.07 Tg (p cc 0.05 0.25 (actual part of the bi-material joint) ( imaginary part of the bi-material joint) (damping of the bi-material joint) Even if the damping of the rolls at X is 0.25, the damping along the XX 'direction is only 0.2. The objective is to minimize the contribution of the stiffness following XX 'of the bread in ZZ' and the stiffness following ZZ 'bread XX' in order to naturally achieve the objectives of depreciation by direction.

  The device shown in FIGS. 5 and 6 has substantially the same structure as that described with reference to the preceding figures.

  However, we are dealing here with blocks 30 and 31 arranged coaxially and separated by a thin tubular element 4.

  Thanks to this structure, the block 31 will be flexible over a short stroke (for example 0.1 mm) in order to filter in particular the noise and the block 30 will have a high stiffness in order to satisfy the objectives of road behavior.

  As an indication, the joint can have the following characteristics: - According to the "damping" direction: - Under a frequency of 1 Herz and a load of 1 mm: K = 100 daN / mm - Under a frequency of 15 Herz and one load of 1 mm: Tg (p = 0.3 - under a frequency of 100 Herz and a load of 1 mm: K = 300 daN / mm - According to the direction "filtering": - Under a frequency of 1 Herz and a solicitation of 1 mm: K = 100 daN / mm - Under a frequency of 15 Herz and a stress of 1 mm: Tgcp = 0,1 - Under a frequency of 100 Herz and a stress of 1 mm: K = 150 daN / mm The The device shown in FIG. 7 differs from that of FIGS. 5 and 6 in that the blocks 30 and 31 are separated by a lamination 5, that the core 2 has a section that is substantially in a square and that the blocks have recesses.

  The manufacturing process of this device is more particularly illustrated in FIGS. 8 and 9.

  Thus, an example of an installation allowing its implementation is shown in FIG.

  This is a press 6 constituted, from top to bottom, an upper plate 63, a mold top plate 60, an upper tray 61, a tray 62 and a tray. a lower press plate.

  The molding piece has the general reference 64.

  To carry out the molding, the outer frame and the central core are placed in the mold. The two materials (for example rubber) are then injected simultaneously. For this, two independent injection units are used. In this case, we are dealing with two vertical injection units as shown by the arrows in phantom 7 and 8, which identify the paths followed by the material.

  The setting of the molding parameters (injection time, injection speed, temperature) will be chosen so as not to depend on the difference in viscosity between the two materials.

  The installation shown in FIG. 9 differs from the previous one only in that a vertical injection unit and a horizontal injection unit 10 are used, as shown by the arrows 7 and 8.

  In Figure 10 is shown a device 1 with, symbolized by lines bearing the reference 9, the two "paths" of injection followed by the material. It should be noted in this regard that there are as many injection points as blocks 30 and 31.

  Note finally that two blocks of materials are in contact with each other at a place where the room is not or little solicited. If this contact took place at an important point of stress, the life of the device would not be very long. The implantation of this zone is determined in particular by the geometry of the part and the manufacturing parameters.

Claims (13)

i   1. A method of manufacturing an elastic articulation device intended to allow the articulation of two elements relative to each other, of the type comprising an axial tubular outer armature (1) adapted to be fitted in the first element, a central tubular core (2) adapted to be connected to the second -5 element, mounted within said frame (1) and axis parallel thereto, and a mass (3) of material elastic member interconnecting said outer armature (1) and said central core (2), which consists of at least a first block (30) of a first material having a high damping value and at least a second block (31) of a second material having a low stiffening value, these first and second blocks (30,31) being contiguous, that is to say in direct contact or via a tubular element of thin, and having a contact surface (5) extending xclusively in a substantially transverse direction, that is to say generally cylindrical, coaxial with the frame and core or essentially radial, characterized in that one molds simultaneously, in particular by injection, said first and second blocks (30,31 ).   2. Method according to claim 1 wherein the molding is performed by injection, characterized in that two vertical injection units are used.   3. Process according to claim 1, in which the molding is carried out by injection, characterized in that a vertical injection unit and a horizontal injection unit are used.   4. Process according to claim 1, in which the molding is carried out by injection, characterized in that two horizontal injection units are used.   5. Method according to one of claims 1 to 4, characterized in that said blocks (30,31) are coaxial.   6. Method according to claim 5, characterized in that between the two blocks (30,31) is interposed a tubular element (4), slit or not, of low thickness, coaxial with said reinforcement (1) and core (2).   7. Method according to one of claims 1 to 4, characterized in that said blocks (30,31) are distributed in substantially identical angular sectors.   8. Process according to claim 7, characterized in that the number of sectors is equal to two.   9. The method of claim 7, characterized in that the number of sectors is equal to four, which are alternately distributed, the blocks (30,31) made of the same material being preferably diametrically opposed.   10. Method according to one of claims 7 to 9, characterized in that said device has at least one recess (F) in the contact zone of said blocks.   11. Method according to one of the preceding claims, characterized in that said outer armature (1) comprises, at at least one of its ends, a peripheral collar (12) which is coated with elastic material, which constitutes an axial abutment. .   12. The method of claim 11, characterized in that said elastic material is made of the same material as that of the first block (30) or the same material as that of the second block (31), or a mixture of both.   13. Method according to one of the preceding claims, characterized in that said tubular frame (1) and central core (2) are coaxial.